JPH04184125A - Vibration measurement device - Google Patents

Abstract

PURPOSE:To prevent occurrence of a suddenly changing signal in a vibration detection signal by driving a switch means generating a pulse of a certain time when a vibration detector is disconnected and/or recovered, and by fixing the vibration detection signal to vibration detection zero level. CONSTITUTION:When disconnection occurs in a vibration detection circuit 9, a disconnection detection circuit 6 operates and its digital output rises to 'H'. At the same time, a relay 7 outputs a detector disconnection alarm. On the other hand, a one shot circuit 10 generates a pulse signal with a certain span, by the rising signal, and excites a relay 13. At this time, as an output contact 14 closes and grounds the output of a buffer circuit 15, a suddenly changing signal generated at a smoothing circuit 5 does not occur in an output of a vibration measurement circuit 1A. Similarly, when a disconnection is recovered, output VD of the circuit 1A has no relation with the generation of the suddenly changing signal. The suddenly changing signal is not generated in the vibration detector signal in the case of disconnection and recovery, which gives no bad influence to other parts.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vibration measuring device that measures the vibration of a rotating body such as a turbine generator and is used as a turbine monitoring instrument, and particularly relates to a vibration measuring device that measures the vibration of a rotating body such as a turbine generator. The present invention relates to a vibration measuring device having a disconnection detection circuit.

[Conventional technology]

FIG. 3 is a block diagram showing a vibration measuring device that has been generally put into practical use. In the figure, 1 is the main body of the vibration measuring device, and 2 is a detection signal Vin from the vibration detector 9.
3 is a capacitor for DC cut, 4 is a detection circuit, 5 is a smoothing circuit, 6
is a disconnection detection circuit that detects the presence or absence of a disconnection in the vibration detector 9;
7 is a relay for outputting an alarm, and 8 is a bias circuit for detecting disconnection of the detector. When the vibration detector 9 is in a normal state, the input signal is generated by the resistance R in the bias circuit 8 and the output resistance of the vibration detector 9. The DC level of Vin is approximately several 10 mV.

Next, the operation will be explained. First, when a disconnection occurs in the vibration detector 9, the DC level of the input signal Vin will be approximately several hundred.
Changes to mV. This change in the input signal Vin is caught by a disconnection detection circuit 6, and a relay 7 is activated to output a detector disconnection alarm P to the outside.

For example, in a normal measurement state where the rotating body is rotating at the rated speed, a DC signal proportional to the vibration amplitude is transmitted to the vibration measuring device based on the signal (Vin) of the vibration detector 9 that is proportional to the vibration speed of the rotating body. is output from main body 1 of.

Next, if the internal coil or signal extraction cable constituting the vibration detector 9 is disconnected, the signal changes as shown in FIG. 4.

In order to simplify the movement when the detector is disconnected, the waveform example in FIG. 4 is shown with the rotating body stopped (no vibration). If the vibration detector 9 shown in FIG. 3 is normal,
Depending on the bias voltage of the disconnection detection circuit 6 of the vibration detector 9, Vin becomes a constant voltage of 5 to 10 mV DC, but when the vibration detector 9 is disconnected, the output signal Vin is output from the bias circuit 8 for detector disconnection detection. Since the voltage value is determined by the voltage division ratio between the resistor R and the detector output resistor R, the above Vin is approximately I
It increases by about V. At this moment, the output VD of the main body 1 of the vibration measuring device takes on an instantaneous sudden change as shown in FIG. 4(c).

FIGS. 4(a) to 4(c) are time charts when the vibration detector is disconnected and restored in the conventional device shown in FIG.

[Problems to be Solved by the Invention] Conventional vibration measuring devices are configured as described above, so that if a coil breakage or a cable breakage occurs inside the vibration detector, the breakage can be recovered. At times, the output of the vibration measuring device may suddenly change transiently, causing problems such as malfunction.

This invention was made to solve the above-mentioned problems, and provides a vibration measuring device that does not cause any sudden change in the output of the vibration measuring device even when the vibration detector is disconnected and when it is restored. The purpose is to

Incidentally, there is a technique described in Japanese Patent Publication No. 2-17683 as an approximation technique.

[Means for Solving the Problems J] The vibration measuring device according to the present invention is provided with a disconnection detection circuit that receives an output signal from a vibration detector and outputs a disconnection signal when the vibration detector is disconnected, and detects the rise and rise of the disconnection signal. The apparatus further includes a pulse generating means for generating a pulse of a constant time width using a falling edge as a trigger, and a switch means for fixing the vibration detection signal to a vibration detection zero state using the pulse.

[Effect]

The pulse generating means in this invention generates a pulse of a certain time width to drive the switch means when the vibration detector is disconnected and when the vibration detector is restored, fixes the vibration detection signal to a vibration detection zero state, and when the vibration detector is disconnected. Also, the sudden change signal output at the time of recovery is prevented from appearing in the vibration detection signal.

[Embodiments of the Invention] Hereinafter, an embodiment of the present invention will be explained with reference to the drawings.In Figure 0, the same parts as in Figure 3 are indicated by the same reference numerals.In Figure 1, IA represents a vibration measuring device according to the present invention. main body, 10.12 is a one-shot circuit that outputs a one-shot pulse of about 5 to 7 seconds, 11 is an inverter circuit, 1
3 is a second relay, and 14 is an output contact of the second relay 13, which functions to short-circuit the output v0 of the main body 1 of the vibration measuring device for a certain period of time. 15 is a buffer circuit. (Here, 10 to 12 are pulse generating means, 13.1
4 is called a switch means. ) Next, the operation of the present invention will be explained with reference to the time chart of FIG. First, the basic measurement operation is the same as that of a conventional vibration measurement device, so a description thereof will be omitted. First, when a disconnection occurs in the vibration detector 9, the disconnection detection circuit 6 operates and its digital output rises to the "H" level as shown in FIG. 2(C). At the same time, relay 7 operates and outputs a detector disconnection alarm via its output contact. On the other hand, when the one-shot circuit 10 catches the rising signal, it generates a pulse signal with a constant time width as shown in FIG.
Excite. At this time, the output contact 14 is closed and the output of the buffer circuit 15 is grounded, so the smoothing circuit 15
As a result, the sudden change signal generated in the vibration measurement circuit does not appear in the output of the vibration measuring circuit (see FIGS. 2(f) to (h)). Furthermore, when the disconnection of the vibration detector 9 is restored, the output of the disconnection detection circuit 6 changes from the "H" level to the "L" level, so the inverter circuit 11 catches this change in the digital signal. and gives the inverted output signal to the one-shot circuit 12. The one-shot circuit 12 is shown in FIG. 2(e) (
When a pulse signal with a predetermined time width is output as shown in f), the second relay 13 is excited in the same manner as described above. Then, since the output contact 14 is closed, the output V of the vibration measurement circuit
As a result, o becomes completely unrelated to the generation of the sudden signal. In the case of normal vibration detection operation, since it is a high frequency pressure signal, the disconnection detection circuit 6 will not malfunction, of course.
A DC signal is output from the buffer circuit 15.

Incidentally, in the above embodiment, an example was explained in which the output contact of the second relay 13 was used as the operation for dropping the output of the buffer circuit 15 to the ground, but an analog switch or the like may be used, for example. It has a similar effect.

〔Effect of the invention〕

As described above, according to the present invention, the pulse generation means and the switch means are provided on the output side of the wire breakage detection circuit so that the vibration detection signal is fixed to the vibration detection zero state when the output signal of the wire breakage detection circuit is received. Therefore, even when the vibration detection circuit is disconnected or restored, no sudden change signal is generated in the vibration detection signal, and as a result, there is an effect that there is no adverse effect on others.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a vibration measuring device according to an embodiment of the present invention, FIG. 2 is a time chart for explaining the operation of the device according to the embodiment, and FIG. 3 is a block diagram showing a conventional vibration measuring device. , FIG. 4 is a time chart for explaining the operation of the above-mentioned conventional device. In the figure, 1 is the main body of the vibration measuring device, 6 is a disconnection detection circuit, 9 is a vibration detector, 10.12 is a one-shot circuit,
11 is an inverter circuit, 13 is a second relay, and 14 is a second relay contact. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] Input the signal corresponding to the vibration speed output by the vibration detector,
A conversion circuit that converts this signal into a displacement proportional signal and outputs it as a vibration detection signal, and a disconnection detection circuit that detects a disconnection in the front vibration detector based on the signal and outputs a disconnection signal indicating that the disconnection occurs when the disconnection occurs. a vibration measuring device comprising: a pulse generating means for outputting a pulse of a certain time width using the rising and falling edges of the wire breakage signal outputted by the wire breakage detection circuit as a trigger; and the pulse generating means outputting the pulse. and a switch means for fixing the vibration detection signal to a zero vibration detection state.